Telephone receiver



.Se u 11;1-92s- I v 1,683,945 N. BALDWIN TELEPHONE RECEIVER Filed Oct. 51, ms I W INVENTQR ill our r; s'rA'rEs PATENT OFFICE.

mo ma BALDWIN, or EAST MILL CREEK, UTAH.

mminrnoun RECEIVER.

' Application fllcd- October 31, 1925. Serial No. 66,037.

The principal. obiect of the present inven 1 tion is to provide afulcruin for the armature Without the spool in such form-that the armature will operate as if the fulcrum were .within the spool; or in other WOKTlQ, to provide a virtual fulcrum for the armature within the Spool. i

I attain this and other objects by the mechanism illustratedin the accompanying drawing in which Fig". l isu section oi an instrument embodying the general principle of the invention; is an elevation of the same instrument from the rear or from the side opposite the diaphragm; Fig. ,3 is a section showings. slight modification of the instrumentsnown in Fig. l; and Fig. l is an eleva tion of the instrument shown in Fig. 3. i

In the several figures of the drawing numoral. l designates the spool containing the actuating coil through which the non-helical ferreous armat-ure 2 passes Without any me .chanical contact. ii -shaped pole-pieces 3, 3 surround the spool 1 with their limbs approaching the armature on either side at its ends, and magnets 4 .45 contact with said polepieces. The armature 2 is held in proper position Within the spool and between the pole 1 pieces by tensionmembers, preferably wires 5, 5 which are mretclied upon the bracket 6 and secured to the armature 2 by solder or other suitable means. The bracket 6 is se curcd'to the magnets 4, 4.

In the mechanism shown in Figs. 1 and 2, the movement of the armature 2 is communicated to an acoustic element such as a dia-.

phragm? by means of. a lever arm 8 mounted upon the armatureEZ and a flexible connecting link 9. The diaphragm 7 is supported by a spring 10 secured to the bracket 6. The tension of the wires or members 5, 5 is adjustable by means oi. the screw 11.

The structure shown in 3 and 4; isthc same as that shown in Figs. 1 and 2 except that the lever arm 8 consists of a yoke passing over thepolepicce? and connecting with both ends of the armature. This gives greater rigidity to the armaturcond lever arm.-

In-either structure it will be-seen that'in'fib operation under the influence of telephonic currents in the coil the armature will be acted upon by e ual and'opposite forces at its o posite ends w ich will cause it to oscillate a out a. point at or near its centers? This movement will be communicated to the dia-/ phragm 7 by means of the lever arm 8 and" flexible connecting link 9. The position of this connecting link is parallel to thetension members 5-, 5 therefore in reacting upon the 6 armature it will have no tendency to displace the armature up or down and the armature will operate in the same manner as if it were pivoted at the center. The armature has no fulcrum,-. but with this particular combina.-

tion of, forces" the tension members are the equivalent of afulcrum, serve the same purpose, and may be said to constitute a fulcruin at the center of the armature. In other words the armature has a virtual fulcrum at the center. This virtual fulcrum and the ails of oscillation of-the armature lie substantially without the supporting means While the connecting link 9 will have a transverse motion with the armature 2 it will also have a longitudinal component due to the lever arm 8 which Will move the diaphragm 7. The mechanical advantage of the system as ap plied to the diaphragm is determined by the distance from the armature at which the con- 8.5

necting link 9 is connected to the lever arm 8.

As here disclosed the armature is'operatively connected with a cone diaphragm of aloud speaker, but it is obvious that the invention can. be used in other kinds of acoustic instru- 9r ments such as inductive transmitters, inductive phonograph reproducers, or electrical phonograph recorders.

I claim:

1. A'telephone receiver comprising an ar- 01 mature operatlvely connected with a diaproducing mechanism and surrounded by an actuating coil,'tension members supporting said armature, and constituting a virtual 10o "fulcrum for said armature. v

3. An acoustic instrument comprismg an armature, an actuating c011 surrounding said tively connecting said armature with said acoustic clcment,' and tension members supporting said armature and constituting a virtuai fulcrum for said armature.

4. An acoustic instrument comprising an armature, annctuating'coil surrounding said si'ncuitute anacoustic element, means operatively connecting said armature with said acoustic element, and tension members supporting said armature and constituting a virtuztl fulcrum for said armaturewithin said coil. i i

5. 'An acoustic instrument comprising a, non-helical ferreous armature, an' acoustic clement, means operatiwcly connecting said armaturcwith sai d acoustic element, and ten 51011 members supporting said armature and constituting a virtual fulcrum for said armature. i v 6. An acoustic instrument comprising-a non-helical ferreous armature, an acoustic element, moans operatively connecting saidv armature with said acoustic clement; supporting moans disposed at either end of said armature and permitting saidarmature to oscillate about u'ipoint betwcen its ends.

. 7. An acoustic instrument comprising an armature. an actuating-coil surrounding said armature, an acoustic clement, means opera tively connecting; said armature with said, acoustic element, and supportlng means-j.

Wholly without said coil and supporting said armature and permittin; said armature to oscillate-about a point within said ,coil.

4 NATHANIEL BALDWIN. 

